Thursday, October 28, 2010

Belize Reef Die-Off Due to Climate Change?

Corals often survive infrequent bleaching, but recovery is a slow process during which corals are vulnerable to other threats. "They can become sort of half-dead," said McField. "They don't just live or die. They're strange creatures. They can become partially dead." McField notes that four years ago, disease outbreaks that followed coral bleaching events killed more coral than the bleaching itself.

"There are lots of diseases out there waiting to attack the coral when it's a bit weakened," she said.

In areas of Belize where live coral cover has died there is still a chance for recovery. Large-scale algae cover, which often overwhelms dying reefs, has not been widespread. This gives biologists hope that the work of other ecosystem actors, such as relatively healthy algae-eating fish populations, may allow coral to recover.

"Since the mass bleaching events, Belize's reefs appear to be under a process or recovery," said Nadia Bood, a reef biologist with the Belize-based Coastal Zone Management Institute. "However, recovery is slow and mean live coral cover is still low."

"The interesting question will be to see the recovery in the coming years. Some reefs are impacted by coastal development, or located close to major sediment-producing and nutrient-filled rivers. Will those reefs in the areas of greater local human threats recover more slowly than those offshore or those in marine protected areas that have higher fish populations?" McField wonders. "Will either recover at all? These ecological disasters have provided the means for a large-scale experiment, but changes here happen on the scale of decades, which is why long term approaches to science and conservation are required."

How to combat such a daunting opponent as global warming? Conservationists say that given the complex factors affecting coral health, much can still be done to aid reefs.

"Rather than throwing up our hands and saying 'we can't control that,' we've got to be even more diligent and try even harder to control local impact[s] such as pollution and over-fishing," McField said.

Also critical are efforts to better identify the characteristics that make reefs resistant to coral bleaching. It's known that higher current flows cool reefs and remove the toxic products of cellular processes, even more resistant coral species can stave off bleaching.

"We have to be prepared for the next bleaching event [and] ready to identify some of these positive things," McField said. "Then perhaps we can build the knowledge we get into the Marine Protected Areas and focus our conservation attention on an area we hadn't beforebecause that might be the area that survives."